macroporous hydrogels based on 2-hydroxyethyl methacrylate. Part 7: Methods of preparation and comparison of resulting physical properties

Five methods of preparation of macroporous hydrogels are described and compared: precipitation polymerization, polymerization in presence of salt, polymerization in presence of gas-releasing compound, lyophilization and electrospinning. Crosslinked copolymers based on 2-hydroxyethyl methacrylate were selected as model hydrogels. Hydrogels were characterized by SEM microscopy, porosity, communicating/non-communicating pore ratio, pore sizes and their distributions. The advantages and drawbacks of the methods of preparation, modification of hydrogel properties, reproducibility and issues related to their preparation are discussed. The most convenient method was preparation in presence of salts. One type of porous hydrogel was based on a hydrogel matrix composed of nanofibers prepared by electrospinning method. The nanofibers have shown unique properties due to their large specific surface. The least suitable method seems to be the preparation of porous hydrogels by polymerization using gas (nitrogen) releasing initiator, 2,2 ́-azobisisobutyronitrile. The use of prepared porous hydrogels is intended especially for scaffolds in tissue engineering.